Monday Nov 24, 2008 (foodconsumer.org) -- A study published in the Nov 2008 issue of Cancer Causes and Control suggests that engaging in exercise or physical activity of any intensity reduces the risk of colon and rectal cancer while being physically inactive increases the risk.

The study involved 488,720 men and women participating in the NIH-AARP Diet and Health Study who were aged 50-71 years at baseline in 1995-1996. Through Dec 31, 2003, 3,240 and 1,482 colorectal cancers among men and women were recorded, respectively.

The study led by Howard R. A. and colleagues from the National Cancer Institute found men engaging in exercise five or more times per week compared to those who were never or rarely exercising were at a 21 percent reduced risk of colon cancer.   For women, the reduction was 15 percent.

In men, exercise also decreased the risk of rectal cancer by 24 percent.

In men, higher intensity of exercise led to higher reduction in the risk of colon cancer.   Low intensity of physical activity (more than or equal to 7 hours per week) was associated with a 19 percent reduction in the cancer risk while moderate to vigorous intensity of physical activity (more than or equal to 7 hours per week) reduced the risk by 18 percent.

In both men and women, physical inactivity or exercise defined as spending more than 9 hours per day (according to the report although it sounds like high) on watching television or videos was associated with a 61 percent increased risk of colon cancer.

Another study said lack of sleep could increase risk of cancer.